A former big shaker in the Beehive has backed the civil servants who told ministers about Winston Peters' years of pension over-payments.
Sir Maarten Wevers has been called as an expert witness in Mr Peters' case being heard at the High Court in Auckland.
Mr Peters is suing former National ministers Anne Tolley and Paula Bennett, the MSD, its former chief Brendan Boyle and current State Services Commissioner Peter Hughes.
His legal action comes after details of his superannuation over-payments were leaked and became public just weeks before the last general election.
Mr Peters wants hundreds of thousands of dollars in damages, which could be paid for by taxpayers if awarded.
Winston Peters claims the department heads were wrong to brief their respective ministers under the "no surprises" policy.
But Sir Maarten, a former CEO of the Department of Prime Minister and Cabinet who's worked directly with or under five prime ministers, has rubbished some of Mr Peters' claims.
"Ministers would expect to be forewarned about this," Sir Maarten told the court.
He said based on his experience it was appropriate for Mr Boyle to brief then Social Development Minister Anne Tolley about the over-payments.
"A high profile, notable and very powerful public figure had received money through the state benefit system that he was not entitled to," he said.
"That followed an error he had made on the form that he had confirmed was correct by way of a statutory declaration.
"That individual was a former Cabinet minister, a senior - in terms of his experience - MP, and the leader of a political party that might have a role in the formation of the next government," he said.
Sir Maarten said former Green Party co-leader Metiria Turei's admission of receiving benefit payments after making false claims had happened at the same time and getting high media attention.
Sir Maarten said it was his view Brendan Boyle's briefing to Anne Tolley met expectations for a no surprises briefing as set out in the Cabinet Manual.
He also said it was significant that Mr Boyle sought advice from the State Services Commission before making the briefing, and he did not rush to judgement.
"This was a matter of potentially high public interest," he said.
Sir Maarten disagreed with many of Mr Peters' claims about how the no surprises policy works.
He said ministers expect to be warned "if the fuse is burning on an issue likely to blow up".
Sir Maarten also supported State Services Commissioner Peter Hughes' own no surprises briefing of former State Services Minister Paul Bennett.
State Services Commissioner takes witness box in own defence
State Services Commissioner Peter Hughes, one of those being sued by Mr Peters, told court his department regularly dealt with information that was far more complex and sensitive.
"Mr Peters states...that ministers have no responsibility for operational matters. With respect, this is incorrect," Mr Hughes said.
He said the "integrity of the public service" was at issue.
"The importance of the issue wasn't that Mr Peters had received money he wasn't entitled to. The importance of the issue was that because of who he was - the fact that this was Mr Peters raised potential for concerns to be raised about special treatment or bias interference in the Ministry of Social Development's processes for dealing with this overpayment," Mr Hughes said.
He rejected allegations that he acted politically as "untrue and unfounded".
He highlighted how important political neutrality was to him personally, saying not even his family knows what his politics are because he never discusses them.
Mr Hughes also took issue with many of the claims made by Winston Peters about how a no surprises briefing should work and when one should happen.
Mr Hughes also told the court he was not behind the leak to media.
"I do not know where the leak came from, I have no insight into that, there are a variety of possibilities and I have no insight into that," he told the High Court.
He said he also has an assurance from his deputy that she did not leak Mr Peters' information.
Speaking about the Ministry of Social Development, Mr Hughes said a leak from a big government agency could never be ruled out.
But he said he never considered it to be a high risk in this case.
Mr Hughes said the then MSD chief executive Brendan Boyle, also being sued by Mr Peters, went to "considerable lengths" to contain the information.
Mr Peters claims in his case that the ministers should not have been told about his case.
Under cross examination from Mr Peters' lawyer Brian Henry, Mr Hughes said it wouldn't have been possible to brief Paula Bennett without identifying him.
He said the briefing would not have made sense if that had happened.
Mr Hughes said he and his deputy "went to great lengths" to protect Mr Peters' privacy and only told Ms Bennett what she needed to know.
'No political motivation' in briefing former minister - Former MSD chief executive
Former MSD chief executive Brendan Boyle said he rejected Mr Peters' claim that his no surprises briefing of then minster Anne Tolley was a sham to disclose his private information to National Party ministers.
"I totally reject the allegation, I had no political motivation in deciding to brief my minister," he told the High Court.
He said his overriding concern was the "accountability of the minister to Parliament" and the potential risk to the government Ministry of Social Development.
"In my years in the public service where I have seen relationship with ministers break down is where there is an absence of the no surprises approach," he said.
"In my experience working with around 38 ministers I have never ever met a minister that didn't want to be informed of something significant in their portfolio - either positive or negative.
"Ministers don't want to be surprised, and the only times that I can recall ever having ministers who were genuinely angry was when they were surprised.
"It's not when something goes wrong, because things do go wrong," he told the court.
Lawyers in the case should start their closing statements tomorrow.